(a) Field of the Invention
The present invention relates to a transflective liquid crystal display and a manufacturing method thereof.
(b) Description of the Related Art
Liquid crystal displays (“LCDs”) are one of the most widely used flat panel displays. An LCD includes a liquid crystal (“LC”) layer interposed between two panels, each panel provided with field-generating electrodes. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer which determines orientations of LC molecules of the LC layer to adjust polarization of incident light. The light having adjusted polarization is either intercepted or allowed to pass by a polarizing film, thereby displaying images.
LCDs are categorized as non-emissive displays, in that they do not produce any form of light. Accordingly, the LCDs utilize artificial light emitted from lamps of a backlight unit separately provided, or ambient light, as a light source. Depending on the light sources employed by the LCD, LCDs are classified as a transmissive LCD or a reflective LCD. The light source of the transmissive LCD includes a backlight, and the light source of the reflective LCD includes an external light. The reflective type of LCD is usually applied to a small or mid-size display device. Recently, transflective LCDs have been under development. The transflective LCD uses both a backlight and an external light as light sources depending on circumstances, and are usually applied to small or mid-size display devices.
The transflective LCD includes a transmissive region and a reflective region in a pixel. While light passes through an LC layer only once in the transmissive region, light passes through the LC layer twice in the reflective region. Accordingly, a difference of color tone between the transmission areas and the reflection areas may occur.
There are two methods to solve the above-mentioned problem. The first method is to form the color filters of the transmission areas to be thicker than the color filters of the reflection areas. The second method is to form light holes in the color filters of the reflection areas.
However, the latter method has some drawbacks. In this latter method, after the formation of the holes, an overcoat layer is coated on all of the color filters in order to compensate a stage difference between the color filters with the holes and the color filters without the holes, thus creating a planarized surface. In this case, however, perfect planarization is technically impossible. Accordingly, even if the overcoat layer is formed on all of the color filters, a cell gap at the reflection area with the holes and a cell gap at reflection area without the holes are different from each other. This difference in cell gaps at the reflection area causes a yellowish display.